If you are being quoted two prices for what looks like the same sink, the grade is usually the reason. This article explains what actually differs between AISI 304 and AISI 201, where each one is defensible in a resale assortment, and how to write the grade into an RFQ so that the quotation you receive is the product you get.

It is written for importers, distributors and private-label brands specifying residential kitchen sinks.

The two grades in one paragraph

Both are austenitic stainless steels and both are used for kitchen sinks in large volumes. AISI 304 is the long-established specification for the application. AISI 201 is a lower-cost alternative in which part of the nickel content is replaced by manganese. The substitution reduces the raw material cost, and it also reduces corrosion resistance. Everything else in this article follows from that one sentence.

Composition: what actually changes

304 is the classic 18/8 composition — roughly 18% chromium and 8% nickel. Chromium is what forms the passive oxide layer that makes stainless steel stainless; nickel stabilises the austenitic structure and contributes to corrosion resistance and formability.

201 keeps the chromium in a similar region but cuts the nickel substantially and compensates with manganese and nitrogen to hold the austenitic structure. The result is a steel that behaves similarly in many respects — it draws, it polishes, it looks the same on the shelf — but with less of the element that helps it resist attack.

That last point is why grade cannot be judged by appearance. A well-finished 201 sink and a well-finished 304 sink are visually indistinguishable in a photograph, on a showroom stand, and on arrival.

Corrosion behaviour in normal kitchen use

Under the same conditions, 201 has lower corrosion resistance than 304. In practice the difference shows up at the margins rather than in normal daily use:

• Chlorides. Salt, and cleaning products containing chlorine bleach, are the most aggressive everyday exposure a kitchen sink meets. This is where the grade difference is most likely to become visible.
• Standing water and residue. Water left to evaporate in the bowl concentrates whatever is dissolved in it. Hard water in particular leaves deposits that hold moisture against the surface.
• Prolonged contact with acidic or salty food waste. Not a problem for hours; potentially a problem over repeated long exposures.

We are not going to publish comparative test figures. We have not run controlled salt-spray or pitting tests on our own production, and quoting numbers from a general reference as if they described our sinks would be dishonest. If a supplier gives you specific hour figures, ask which laboratory produced them and on which sample.

Where 201 is chosen, and why

201 is not a defect. It is a cost position, and it is a legitimate one when the buyer is choosing it knowingly.

It tends to make sense where the retail price point is the binding constraint and the alternative is not selling at all; where the sink is going into a rental, developer or entry-level fit-out with a short expected service horizon; and where your after-sales exposure is short and clearly stated.

It tends not to make sense where you are carrying a multi-year warranty, where the end market has hard or chloride-heavy water, or where the brand promise is built on durability. In those cases the material saving is smaller than the cost of a single wave of returns.

Where 304 is the safer specification

Choose 304 when any of the following apply:

• You are building an own-brand line and your name is on the product
• Your warranty or return policy runs longer than a year
• The destination market has aggressive water chemistry
• You are selling into kitchen furniture manufacturers or project channels, where a failure affects an entire installation batch
• You simply do not want to have this conversation with a customer later

The premium is real but it is a material premium, not a multiple.

Water quality and cleaning products

Grade choice interacts with what the end user does, and this is worth putting into your own product documentation.

The most common "rusty sink" complaint is not corrosion of the sink at all. It is iron particles — from steel wool, from an unseasoned cast-iron pan, from a chipped knife, from the water supply itself — sitting on the surface and oxidising there. The marks are orange, they look exactly like rust, and they clean off with a non-abrasive stainless cleaner. This happens on 304 as readily as on 201.

Genuine base-metal corrosion is rarer and is driven by grade plus prolonged aggressive exposure. Telling the two apart saves an enormous amount of warranty argument, and a short care instruction in the carton prevents a meaningful share of complaints.

Surface finish is not a substitute for grade

Finish changes how the surface looks and how it hides marks. It does not change the metallurgy underneath. A brushed or textured 201 sink still has 201's corrosion behaviour, and a coating applied to the visible surface does not alter the base material.

Specify grade and finish as two separate lines in the RFQ. Do not accept a quotation where the finish is described in detail and the grade is not mentioned.

How to state the grade in your RFQ

Write it explicitly, and ask for confirmation in the quotation rather than only in the conversation:

Steel grade: AISI 304
Grade to be confirmed in the proforma invoice and on the packaging
Material documentation: state what is available for this order

That last line matters. Ask what material documentation the supplier can actually provide for your specific order, and treat any answer that is vague as an answer. Do not assume mill documentation is included unless it is confirmed in writing for that order.

If you are ordering a mixed assortment, state the grade per model. It is common for a range to run 304 on the upper models and 201 on the entry positions, and an unstated grade will default to whatever is cheapest to produce.

What we supply

We produce pressed (drawn) stainless steel sinks as our core in-house line and handmade (welded) stainless steel sinks as a supplementary in-house line. Grade is specified per order, and we will confirm it in writing in the quotation and on the packaging.

If you are unsure which grade fits your channel, tell us the destination market, the retail price position and the warranty you intend to offer, and we will tell you which way we would specify it — including when we think 201 is the right commercial answer.

Common misunderstandings

• "Magnetic means it is not stainless." Not a reliable test for this comparison. Magnetic response varies with cold working and does not cleanly separate 304 from 201.
• "18/10 is better than 18/8." Marketing shorthand from tableware. Not a meaningful sink specification.
• "Thicker means better steel." Thickness and grade are independent. A thick 201 sink is still 201. See stainless steel sink thickness explained.
• "The finish will protect it." It will not. See above.

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